Basic Wastewater Operator Practice Exam

What is the purpose of an air-gap in a water system?

1. To take the gap of air and create space for more bugs

2. To prevent contamination of potable water systems

3. To allow for less air to enter the system

4. To discharge excess air in the pressure line

The correct answer is: To prevent contamination of potable water systems

An air gap is a critical component in a water system designed to maintain a physical separation between the drinking water supply and any potential contaminants. The primary purpose of an air gap is to prevent the backflow of contaminated water into the potable water system. This separation ensures that if there is a drop in pressure or an unexpected siphon effect, non-potable water cannot flow back into the clean water supply, safeguarding public health by protecting drinking water quality. In practical terms, an air gap is typically established at locations such as faucets or discharge points, where the physical elevation difference creates a barrier that cannot be bypassed by liquid. This design is a fundamental principle in cross-connection control and helps uphold sanitary conditions in potable water systems. Maintaining such barriers is essential in preventing issues such as back-siphonage and backpressure, both of which pose risks to water safety.